To choose the correct chainring, 1) determine the number of teeth (they're usually marked, or simply count them), 2) determine how many bolt holes there are (usually 4 or 5), and 3) determine the Bolt Circle Diameter (BCD; see diagram).

Finding the number of teeth and bolts holes is easy. If you don't know your chainring's BCD, measuring it is tricky. So, instead, measure the exact distance (center to center) between 2 adjacent bolt holes. Then find that number on the correct chart below to determine the BCD for your chainring.

BCD Chart for 5-bolt Chainrings

Bolt to Bolt (measure center to center)

Bolt Circle Diameter (BCD)

32.9mm

56mm

34.3mm

58mm

43.5mm

74mm

55.4mm

94mm

64.7mm

110mm

76.4mm

130mm

79.5mm

135mm

84.6mm

144mm

BCD Chart for 4-bolt Chainring

Bolt to Bolt (measure center to center)

Bolt Circle Diameter (BCD)

41mm

58mm

45.3mm

64mm

48.1mm

68mm

73.6mm

104mm

79.2mm

112mm

If you have any questions concerning chainring compatibility, please contact us.

Part Numbers

Option

UPC

MPN

50T

710845665820

11.6215.198.010

52T

710845674693

11.6215.198.050

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SRAMRed Outer Chainring (Compact)

$99.00 - $103.00

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